Trying to decide how to sell..

Sell the Dart whole, with all of the stuff from the Duster still in it and running. The sentimental value of the 340, 4 spd, and 8 3/4 Sure Grip will only mean something to you. If you're really attached to the dead Duster parts, pull it all out, sell the Dart, and then buy a 70 Duster body and build a replica of the one you mashed up.